linux-kernel - RE: [PATCH 1/2] hyperv-fb: add pci stub

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Date:	Wed, 2 Oct 2013 14:29:28 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Gerd Hoffmann <kraxel@...hat.com>
CC:	Haiyang Zhang <haiyangz@...rosoft.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	"open list:Hyper-V CORE AND..." <devel@...uxdriverproject.org>,
	"open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] hyperv-fb: add pci stub



> -----Original Message-----
> From: Gerd Hoffmann [mailto:kraxel@...hat.com]
> Sent: Wednesday, October 02, 2013 4:55 AM
> Cc: Gerd Hoffmann; KY Srinivasan; Haiyang Zhang; Jean-Christophe Plagniol-
> Villard; Tomi Valkeinen; open list:Hyper-V CORE AND...; open list:FRAMEBUFFER
> LAYER; open list
> Subject: [PATCH 1/2] hyperv-fb: add pci stub
> 
> This patch adds a pci stub driver to hyper-fb.  The hyperv framebuffer
> driver will bind to the pci device then, so linux kernel and userspace
> know there is a proper kernel driver for the device active.  lspci shows
> this for example:
> 
> [root@...p231 ~]# lspci -vs8
> 00:08.0 VGA compatible controller: Microsoft Corporation Hyper-V virtual
> VGA (prog-if 00 [VGA controller])
>         Flags: bus master, fast devsel, latency 0, IRQ 11
>         Memory at f8000000 (32-bit, non-prefetchable) [size=64M]
>         Expansion ROM at <unassigned> [disabled]
>         Kernel driver in use: hyperv_fb
> 
> Another effect is that the xorg vesa driver will not attach to the
> device and thus the Xorg server will automatically use the fbdev
> driver instead.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/video/hyperv_fb.c | 40
> +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/video/hyperv_fb.c b/drivers/video/hyperv_fb.c
> index 8ac99b8..8d456dc 100644
> --- a/drivers/video/hyperv_fb.c
> +++ b/drivers/video/hyperv_fb.c
> @@ -795,12 +795,21 @@ static int hvfb_remove(struct hv_device *hdev)
>  }
> 
> 
> +static DEFINE_PCI_DEVICE_TABLE(pci_stub_id_table) = {
> +	{
> +		.vendor      = PCI_VENDOR_ID_MICROSOFT,
> +		.device      = PCI_DEVICE_ID_HYPERV_VIDEO,
> +	},
> +	{ /* end of list */ }
> +};
> +
>  static const struct hv_vmbus_device_id id_table[] = {
>  	/* Synthetic Video Device GUID */
>  	{HV_SYNTHVID_GUID},
>  	{}
>  };
> 
> +MODULE_DEVICE_TABLE(pci, pci_stub_id_table);
>  MODULE_DEVICE_TABLE(vmbus, id_table);
> 
>  static struct hv_driver hvfb_drv = {
> @@ -810,14 +819,43 @@ static struct hv_driver hvfb_drv = {
>  	.remove = hvfb_remove,
>  };
> 
> +static int hvfb_pci_stub_probe(struct pci_dev *pdev,
> +			       const struct pci_device_id *ent)
> +{
> +	return 0;
> +}
> +
> +static void hvfb_pci_stub_remove(struct pci_dev *pdev)
> +{
> +}
> +
> +static struct pci_driver hvfb_pci_stub_driver = {
> +	.name =		KBUILD_MODNAME,
> +	.id_table =	pci_stub_id_table,
> +	.probe =	hvfb_pci_stub_probe,
> +	.remove =	hvfb_pci_stub_remove,
> +};
> 
>  static int __init hvfb_drv_init(void)
>  {
> -	return vmbus_driver_register(&hvfb_drv);
> +	int ret;
> +
> +	ret = vmbus_driver_register(&hvfb_drv);
> +	if (ret != 0)
> +		return ret;
> +
> +	ret = pci_register_driver(&hvfb_pci_stub_driver);
> +	if (ret != 0) {
> +		vmbus_driver_unregister(&hvfb_drv);
> +		return ret;
> +	}
> +
> +	return 0;
>  }
> 
>  static void __exit hvfb_drv_exit(void)
>  {
> +	pci_unregister_driver(&hvfb_pci_stub_driver);
>  	vmbus_driver_unregister(&hvfb_drv);
>  }
> 
> --
> 1.8.3.1
Gerd,

Thanks for doing this. This certainly will address some of the issues that are reported. I do have a question though - how would this work if we don't have PCI bus in the guest.

Regards,

K. Y
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